In microwave systems such as communication systems and phased array antenna systems, microwave circuitry is often implemented in the form of what is commonly known as a microwave monolithic integrated circuit (MMIC). MMICs are a type of integrated circuit (IC) device that operates at microwave frequencies (1 GHz to 300 GHz). An MMIC device typically performs functions such as microwave mixing, power amplification, low noise amplification and high frequency switching. Inputs and outputs on MMIC devices are frequently matched to the standard 50 ohms.
As stated, one function performed by an MMIC device is power amplification. Typically, an MMIC device employs a group of FET based distributed amplifiers to provide broadband amplification. FET based distributed high power amplifiers suffer from large gain variation due to leakage and low early voltage. Such gain variations and leakage may cause degraded linearity and distorted output signals. Linearity is determined by a power amplifier's operating range on a characteristic curve that relates its input to output variables, i.e., the more linear the operating range the more linear the power amplifier is said to be. Linearity is a desired characteristic of a power amplifier. In one aspect, for example, it is desired that a power amplifier uniformly amplifies signals of varying amplitude, and/or phase and/or frequency. Accordingly, linearity is an important determiner of the output signal quality of a power amplifier.
Consequently, a system and method for providing a AlGaN/GaN based digital controlled broadband MMIC power amplifier providing increased linearity and gain control is needed.